mpc82x54a Megawin Technology, mpc82x54a Datasheet - Page 54

• Manufacturer Part Number: mpc82x54a
• Description: 8-bit Micro-controller
• Manufacturer: Megawin Technology

Analog to Digital Converter
54
The ADC on MPC82x54A is an 10-bit resolution, successive-approximation approach, and
medium-speed A/D converter. V
internal voltage-scaling DAC use, and the typical sink current on it is 600uA ~ 1mA. For
MPC82x54A, these two references are internally tied to VDD and GND, separately.
Conversion is invoked since ADCS bit is set. Prior to ADC conversion, the desired I/O ports for
analog inputs should be configured as input-only or open-drain mode first. The conversion
takes around a fourth cycles to sample analog input data and other three fourths cycles in
successive-approximation steps. Total conversion time is controlled by two register bits –
SPEED1 and SPEED0. Analog input source comes from P1.x, one of the eight-channels is
multiplexed by analog multiplexer into the comparator. When conversion is completed, the
result will be saved onto {ADCV[7:0], ADCVL[1:0]} register. After the result has been loaded
onto {ADCV[7:0], ADCVL[1:0]} register, ADCI will be set. ADCI associated with its enable
register AUXR.4(EADCI), shares ESPI bit with SPI block to control the interrupt. ADCI should
be cleared in software. The ADC interrupt service routine vectors to 2B
enters idle mode or power-down mode, the power of ADC is turned off by hardware.
P1.7(AIN7)
P1.6(AIN6)
P1.5(AIN5)
P1.4(AIN4)
P1.3(AIN3)
P1.2(AIN2)
P1.1(AIN1)
P1.0(AIN0)
{ADCV,ADCVL[1:0] = 1024 X
10-bit DAC
REFP
+
-
Comparator
MPC82x54A Data Sheet
10
/ V
ADCON
REFM
SPEED1 SPEED0
is the positive/negative reference voltage input for
Approximation
ADCI ADCS
V
Successive
ADCTL Register
Vin – V
Regiter
REFP
- V
CHS2 CHS1 CHS0
REFM
REFM
B9
B8
-
B7
ADCV Register
-
B6
-
ADCVL Register
B5
-
H
B4
. When the chip
-
B3
-
MEGAWIN
B2
B1
B0